The present invention relates to solar concentrators and, more particularly, to a solar concentrator including an optical tracking system.
Solar power systems fall generally into two categories: fixed position flat panels and tracking concentrator systems. Fixed position flat panel systems employ one or more stationary panels that are arranged in an area having an unobstructed view of the sun. As the earth rotates, the sun's rays move over the stationary panel(s) with varying degrees of intensity depending upon geographic location, the time of day and the time of the year. In contrast, solar concentrator systems collect, and focus the sun's rays onto one or more solar cells. Certain solar concentration systems employ tracking systems that follow the sun's path in order to enhance energy collection. Simply put, fixed position flat panels represent a passive solar collection system, while solar concentrator systems represent a more active energy collection system.
Solar concentrator systems utilizing photovoltaic cells typically operate at or below about 500 suns concentration. Operating at higher sun concentration levels creates cooling challenges. In order to address the cooling challenges, certain solar concentration systems employ liquid cooling systems such as found in U.S. Pat. No. 4,081,289. In the '289 patent, a sphere contains a liquid medium and a plurality of fixed solar panels. The sphere acts as a lens and the liquid as a focal and cooling medium. The liquid is circulated within the sphere to carry away heat generated by solar rays impacting the fixed solar cells. In addition to serving as a heat exchange medium, the liquid, in combination with the sphere, focuses the sun's rays toward the fixed solar cells. While effective as a cooling medium, the use of the sphere and liquid to focus light imparts significant limitations on energy collection. That is, the actual focal point of the light passing through the sphere and the liquid is outside of the sphere itself.
Solar concentrator systems allow the use of fewer semiconductor elements to produce a given amount of electric power. However, the use of fewer semiconductor elements results in a need for optics and a system for tracking the sun. At present, the additional cost associated with the necessary optics and tracking systems does not exceed the cost benefit of a reduced number of solar cells.